NSBU dieing?

[chessy56]

This may be an old issue, but there's too many posts to go through. My 2001 Silverado has what I believe may be a NSBU switch that is starting to fail. I have no SES or DTCs indications. It still shifts into R and D w/o problem- tranny appears to run normally. My shift selector display will not highlight the P, N, D or 2 gear postions, but it will highlight the R, 1 & 3 positions. I've had the NSBU switch replaced once before. Truck has ~225K miles on it. It's sloppy, snowy, crappy and wet around WI about now. I think the p/n for the NSBU is 29540479. Is this a correct number? Does my description of the symptoms seem to indicate the switch is beginning to fail? My tranny has NOT gone into any limp mode yet (pounding on wood!).

One other question: Are the 3 harness connectors just straight conductors or are there diodes in line with the wires? These connectors were replaced once before, but the dealer did a lousy splice job and I had to have another dealership redo the splices. Any thoughts?

Any response would be appreciated. Thanks.

[More Power]

You're right, there are quite a few threads here about the NSBU. Many of them describe the symptoms of a failing part. I'd recommend spending some time looking.

That said, I'd also carefully examine the splicing job... Unless the splice was sealed against moisture, they may need attention. It'd be too bad if a new switch didn't fix it, when all it needed was a re-splice.

Let us know how it goes.

Jim

[chessy56]

Splices look good and appeared to be well sealed. When the unit gets wet, I usually got a SES light and a DTC generated. If the tranny was warm, I'd shut off the truck and let it sit for a few minutes. After a restart, the tranny appears to function normally again. It's been some 6 months of running w/o a switch failure, but I'm carrying one as a spare just in case, waiting for the wet, sloppy weather to return. Now, if I can find a way to either seal this thing up or shield it from the wet slop on the roads.....